FALLUJAH, Iraq - Hundreds of reinforcements joined Marines besieging Fallujah on Saturday, and the military said it would move to take the entire city if negotiations fail. Fighting raged through the center of the country, killing 40 Iraqis and an American airman. Gunfire crackled in Fallujah even as Iraqi government negotiators met with city leaders, trying to persuade them to hand over militants who killed and mutilated four Americans in the city March 31. Nearly 60,000 Fallujah residents — about a third of the population — have streamed out of the city over the past two days, a Marine commander...